1. Field of the Invention
The present invention relates to an on-vehicle navigation system that displays for searching facilities located within a specific distance from the next exit of a highway on which the vehicle is traveling, and facilities located within a specific distance from the vehicle which are located along the guide route.
2. Related Art
The navigation system includes a map data storage unit such as a CD-ROM, DVD-ROM, etc., which stores map data (hereafter, simply referred to as xe2x80x9cCD-ROMxe2x80x9d), a display unit, a GPS receiver, and a sensor that detects the current position and current orientation of the vehicle, such as a gyro and a speed sensor. The navigation system reads the map data for the area surrounding the current position of the vehicle from the data storage unit, draws on the display screen a map image surrounding the vehicle position on the basis of the map data, displays a vehicle position mark (location) superimposed on the display screen, scrolls the displayed map image in accordance with the movement of the vehicle, and moves the vehicle position mark with the map image fixed on the screen, so that the driver can determine exactly where the vehicle is traveling at a glance.
Further, the on-vehicle navigation system normally incorporates a guide route function, whereby the user can travel easily to a desired destination without taking the wrong roads. This guide route function automatically searches a route from the starting point to the destination according to the lowest cost, by using the map data and making a simulation calculation using the breadth-first search technique, or the Dijkstra method, and stores the searched route as a guide route. During traveling, the guide route is drawn on the map image thicker with a different color than other roads, and when the vehicle approaches within a certain distance an intersection where it should change course on the guide route, an arrow is drawn on the map image to indicate the direction at the intersection that the vehicle should follow, to thereby guide the user to the destination.
Here, the cost represents the value obtained by multiplying the distance along the road by a constant specified in accordance with the breadth of the road, the type of the road (general road or highway, etc.), right-turn and left-turn, etc., and the estimated travel time of the vehicle, which shows the relative appropriateness of the guide route with a numeric value. Even if there are two routes having the same distance, the cost differs depending on whether the user takes a toll road or not, or whether the user gives preference to the travel distance or to the travel time.
The map stored in the map data storage unit such as a CD-ROM is partitioned into a latitude breadth and a longitude breadth of an appropriate size, in accordance with a scale such as {fraction (1/12500)}, {fraction (1/25000)}, {fraction (1/50000)}, {fraction (1/100000)}, etc., in which the roads are stored as coordinate sets of nodes expressed by the longitudes and the latitudes. The road includes connections of more than two nodes. The part connecting two nodes is named a link. The map data is configured with (1) a road layer including road lists, node tables, and intersection configuration node lists, etc., (2) a background layer for displaying roads, buildings, facilities, parks, rivers, etc., on the map, and (3) a character/symbol layer for displaying the characters and map symbols of administrative boundary names such as municipal names, road names, intersection names, names of buildings, etc. Further, the navigation system includes a mode to guide the user to a destination by means of an arrow display, rather than the foregoing system to display a map.
For the map display mode, the navigation system displays a vehicle mark indicating the vehicle position as well as a map of the area surrounding the vehicle, and always give the user the map information of the area surrounding the vehicle, whereby the user can find the current position of the vehicle at a glance.
A navigation system that does not have the map display mode, but gives route guidance to a destination only by the arrow display, can reduce the size of the display screen because it does not display a map. Further, the system guides the user with a simple arrow display, which the user can easily grasp at a glance during driving, which is safer while driving the vehicle.
In using a conventional navigation system, where a user sets a destination and travels a highway according to the route guidance, when the user suddenly wishes to stop by a facility off the highway, it is difficult to know the exit from which the user should exit the highway to reach the desired facility. For example, while traveling a highway to a destination, when the user wishes to stop by a restaurant for having a meal on the way, it is difficult with the conventional navigation system to effectively judge the exit from which the user should get off the highway to get to a nearest restaurant.
A navigation system that guides the user to a destination only by the arrow display instead of the map display is not provided with means to display facilities located along the guide route, during traveling on the guide route. Accordingly, when the user wishes to stop by a facility (for example, a gas station) located on the way while driving to the destination, it is difficult with the conventional navigation system to know which facilities are located along the guide route. Because it is difficult to know which facilities are available along the guide route, with a navigation system that executes route guidance only by the arrow display instead of the map display, the user is inconvenienced.
For example, while using the navigation system that guides the user to the destination by the arrow display without displaying a map, and traveling the guide route to the destination by following the arrow display, if the user desires to stop by a gas station to refill, since the conventional navigation system presents only the arrow display that guides the user to the destination, it is difficult to know how far the user should travel the guide route to reach the gas station.
Therefore, it is an object of the present invention to provide an on-vehicle navigation system that stores a list of facilities located within a specific distance from an exit of a highway for each exit of a highway, and facilitates searching for the facilities accessible from a next exit while traveling the highway.
Another object of the invention is to provide an on-vehicle navigation system which guides a user to a destination by an arrow display without displaying a map, which gives the user an easily understandable display of facilities located along the guide route.
In order to accomplish the foregoing objects, one aspect of the present invention provides an on-vehicle navigation system that guides a vehicle to a destination, which comprises: a vehicle position detection means that detects the current position of the vehicle; a map data storage means that contains map data including exits of a highway and facilities; a facility search means that searches, from the map data, facilities located within a specific distance from the next exit of the highway, on the basis of a vehicle position detected by the vehicle position detection means, while the vehicle travels the highway; and a display means that displays the facilities searched by the facility search means. The above configuration will search and display the facilities that can easily be accessed from the next highway exit during travel on the highway.
In accordance with another aspect of the invention, an on-vehicle navigation system that guides a vehicle to a destination by an arrow display without displaying a map comprises: a vehicle position detection means that detects the current position of the vehicle; a map data storage means that contains map data including positions and names of facilities; a destination input means for entering destinations; a guide route search means that searches a guide route to the destination entered by the destination input means; a facility search means that searches, from the map data, facilities located within a specific distance from the vehicle position which are located along the guide route searched by the guide route search means; and a display means that displays the facilities searched by the facility search means together with the distances from the vehicle position.
Thus configured, the on-vehicle navigation system that guides a vehicle to a destination by an arrow display without displaying a map will display the facilities located along the guide route together with the distances from the vehicle position.